A Chip Is Born: Inside a State-of-the-Art Clean Room

If you wish to compose an e-mail, index a database of web pages, stream a kitten video in 720p or render an explosion at 60 frames per second, you must first build a computer.

And to build a computer, you must first design and fabricate the tiny processors that rapidly churn through the millions of discrete computational steps behind every one of those digital actions, taking a new step approximately 3 billion times per second.

To do all this, you are probably going to need chip-manufacturing machines from Applied Materials, one of the main suppliers of such equipment to the semiconductor industry.

Because those processes aren't exactly friendly to humans, much of this work happens inside sealed chambers where robot arms move the wafers from one processing station to another. The machines themselves are housed within clean rooms whose scrubbed air (and bunny-suited employees) keep the risk of aerial contamination low: A single dust particle from your hair is all it takes to ruin a CPU that might sell for $500, so companies are eager to minimize how often that happens.

Its 39,000 square feet of ultraclean workspace equals about 81 yards of a football field, and is divided into three huge "ballrooms," each of which is crammed full of Applied's multimillion-dollar machines, alongside pipes, tubes, spare parts, tanks of caustic chemicals, Craftsman tool chests and huge racks of silicon wafers. To get inside, you must suit up in a bunny suit, with a face mask and goggles, two pairs of gloves, and shoe-covering footies. We couldn't even take a reporter's notebook inside: Instead, Applied's staff gave us a shrink-wrapped, specially sanitized clean-room notebook and clean-room pen to use.

It's not a manufacturing facility. Instead, this clean room simulates the fabs where Applied's machines will be used, enabling the company (and its customers) to test out new techniques and processes before putting them on the production line. As such, it provides a rare glimpse inside the world of cutting-edge semiconductor manufacturing.

Top photo: Jon Snyder/Wired.com
Bottom photo: Intel

Photomask

The heart of chip manufacturing is lithography. It's like silkscreening, except instead of squeegeeing ink through a silk template onto a cotton T-shirt, you're shining ultraviolet light through a glass photomask onto a silicon substrate coated with an organic compound called photoresist.

Where the UV light shines through, it chemically weakens the photoresist, leaving a pattern on the surface of the silicon. Then the wafer is sent through a chemical bath that etches trenches into the exposed substrate, while leaving the areas covered by the photoresist untouched.

After removing the photoresist, other machines can fill those trenches with various materials, such as copper or aluminum, that comprise the components of the processor.

Shown here is a photomask, which bears the patterns that will be printed onto a wafer.

Photo: Jon Snyder/Wired.com

Deposit, Etch, Repeat

As a wafer is sent through the manufacturing facility, it can go through as many as 250 different steps. These processes include depositing films of various materials, then etching them to form transistors and copper wiring.

On the right is one of Applied Materials' Endura machines. The Endura platform is a modular, configurable system used to deposit metals and metal alloys on the wafer. It has been used in the manufacturing of almost every chip made in the past 20 years, according to Applied.

On the left is an Applied Tetra III advanced reticle-etch system. This system is used by virtually every maskmaker in the world for the development and production of 45-nanometer masks.

Because it's developing and testing new manufacturing equipment, a huge amount of Applied's expenditures go towards research. In 2009, the company spent $934 million, or about 20 percent of its revenue, on R&D.

Photo: Jon Snyder/Wired.com

The current state of the art for chip manufacturing is 30 nanometers, which means the average size of a chip component is just 30 billionths of a meter across.

Chip manufacturers are currently working on 22-nanometer designs, which are even smaller.

Adding to the challenge is the fact that some of these features are far deeper than they are wide -- in some cases, by a factor of 60 to 1. That means the etching systems have to be capable of creating extremely deep and narrow trenches in silicon, at the nanometer scale, with immense precision.

The lithography room is lit with yellow light to avoid interference with the UV light used with the photomasks.

No Metal Here

The silver metal device on the right side of this Centura machine is a batch loader, used to quickly depressurize a stack of wafers prior to feeding them into the machine for processing.

The green "metal free tool" sign indicates that this machine is used in a part of the process prior to the addition of copper circuits. Copper is a contaminant that can mess up nonmetallic stages of the manufacturing process, so the machines that add copper need to be carefully segregated.

Photo: Jon Snyder/Wired.com

FOUP

Over the past several decades, the wafers upon which chips are made have steadily increased in size, enabling manufacturers to cram more chips on each disk. Since 2000, the industry standard has been 300 mm [about a foot in diameter].

To simplify transportation and minimize the risk of contamination, fabs make use of "front-opening unified pods," or FOUPs. Each one holds 25 wafers in a sterile, clean environment.

FOUPs can be docked onto the front of most of Applied's machines. The machines then suck the wafers inside and automatically process them one-by-one in quick succession.

Photo: Jon Snyder/Wired.com

Automation and Storage

Because a front-opening unified pod full of silicon wafers can be heavy (around 20 pounds), automation is a key aspect of clean-room design.

Applied's clean room has an overhead robotic monorail that transports FOUPs from place to place. In the sealed room shown here, up to 700 FOUPs (containing 17,500 wafers) can be stored until they're needed. Robot arms move the pods in and out of the racks on either side and onto an overhead monorail (not shown in this photo) that runs around the entire cleanroom.

Another 2,800 FOUPs can be stored in the level below the main clean room.

Every machine in a modern clean room is built around 300-mm wafers. The next generation of chips will be made on 450-mm wafers, enabling even larger economies of scale. But because companies will have to replace every single piece of equipment in order to work with 450-mm wafers, many are understandably reluctant to make the switch.

When the transition does happen, it will be the end result of many, many long negotiations among companies like Applied Materials, Intel, AMD and others.

Photo: Jon Snyder/Wired.com

Precision Manufacturing

Computer chips are only about the size of a fingernail, yet contain hundreds of millions of transistors, not to mention all the wiring needed to connect those transistors into a working machine and connect it to a motherboard and the rest of the world.

They're made on circular silicon wafers about a foot in diameter, each of which can contain 200 separate but identical processors.

And because contamination does happen occasionally, despite the purity of the clean room, manufacturers have to test every single one of those processors to make sure that its half-billion components, each of which is only about 30 to 45 nanometers wide, contain no manufacturing defects.

It's no wonder that these types of machines can cost up to tens of millions of dollars (though most are single-digit millions). A full-blown fab, which might contain hundreds of such machines, can cost billions of dollars to build.

And yet the factories pay for themselves. Worldwide semiconductor sales totaled $226.3 billion in 2009, and companies like Intel are among the most profitable corporations in the world.

Photo: Jon Snyder/Wired.com

Mail Break

The bunny-suited engineers and technicians who work in the clean room are responsible for setting up and monitoring the processes that go on inside the machines. But once a process is running, it's largely automated, which leaves downtime.

It took us about 10 minutes to get into or out of our multilayered bunny suits. And though experienced workers can do it in just a few minutes, it's enough of a hassle that once you're in the clean room, you generally want to stay in for awhile.

As a result, workers use laptops inside the clean room to take care of other business while the machines are running. They analyze data, write reports and even check Gmail.

When they do, they're using chips that started out in a room much like this one.